OPHTHALMIC INSITU GEL - AN OVERVIEW
Jaghatha T.*, Kumaran J., Aparna P., Rajesh R. S. and Subash Chandran M. P.
Occular drug delivery is one of the most interesting and challenging endeavor facing the pharmaceutical scientist. The poor bioavailability of conventional ophthalmic formulations (solutions, suspensions, and ointments) is due to rapid precorneal drug loss (through dilution and drainage from the eye) high variability in efficiency, and blurred vision etc. so there was a need for developing advanced drug delivery system. There are some static and dynamic barriers which affects the bioavailability of drug. To overcome the conventional drug therapy drawbacks the polymeric systems are in solution form before administering in the body, but once administered these systems undergo gelation. In situ gels are the liquid preparations which upon instillation undergo phase transition in cul-desac of the eye to form a viscous gel and this occurs due to the environmental changes in the eye. This novel drug delivery system promotes the importantly ease and convenience of administration, deliverance of accurate dose as well as to prolong residence time of drug in contact with mucosa. The primary requirement of a successful control release product focuses on increasing patient compliance, good stability and biocompatibility characteristics which make the in situ gel dosage forms very reliable. This review is to specify the basic anatomy and physiology of human eye, various approaches used for formulation of in-situ gels and polymers used in the formulation of in situ gels. These systems are evaluated for drug content, clarity, pH, gelling capacity, viscosity, in vitro drug release studies, texture analysis, sterility testing, isotonicity evaluation, accelerated studies and irritancy test. FT-IR spectroscopy is used to know drug and polymer incompatibilities.[Full Text Article]